An edit to my previous post #13.

More random thoughts!

I want to add that Remington would have had an improvement in the Hepburn, at least for some folks, with the under-lever and tipping breech block versus the standard breech block that runs straight up and down.  The camming action that pushed in a tight shell would be beneficial and similar to Stevens and Ballard.  Tom does mention this in his book.

If one reads through my build you will also see that Remington made two versions of the tipping block action, in the two known rifles.  Both versions are different from each other and both are different from the patent drawing.  I believe the version I built is the most robust and simplest to make of the three versions.

I may be wrong on my thoughts in post 13 and am always open to others thoughts. There is no way to be sure I’m correct until I could see several Walkers disassembled, which is unlikely, I do not know if they all have the radius cut for the tipping breech block.  Then, if they do, we would see/know if the screw was required to stabilize the breech block in its travels up and down.  It make sense, at least to me, since the screw hole was already incorporated into the patent design, that they would use it to keep the block stable in the Walker design we see today.  It would be a cheap solution.

The other thing I don’t think I have ever mentioned is the breech block design or engineering for the tipping block version.  It’s nothing really special except for the top shoulder of the side rails, that travel in the frame.  They need to be correct in shape and height so that the breech block can drop and fall away from the barrel, but more importantly, so on closing, the block covers the shell base for camming and can move smoothly past the radius cut in the frame previously mentioned.  

If these breech block were already made for tipping, then again, the side screw would be an easy cheap solution to stabilize the breech block in the frame.
Bob